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Coasts

Introduction a range of techniques that you can use for fieldwork in coastal environments. These techniques can be used in the traditional way to study and analyse coastal processes and landforms. Alternatively, why not update your fieldwork slightly to investigate one of the topical and relevant issues in the list below, using the same set of techniques.

Coastal investigations - Why not try...?

  • Investigating the value which people place on a local beach
  • Investigating a litter problem or another issue: why does it happen there, who is most responsible and what is their perception of the beach environment, how might the issue be resolved or minimised
  • Investigating coastal management strategies, for example groynes as habitats. What lives on or around them? How might their removal affect the ecosystem
  • Investigating water quality at the local beach - does it deserve its blue flag? Should it have one
  • Undertaking a cost-benefit analysis of coastal protection measures at a particular location
  • A ‘what would happen if...?' study. For example, what would happen if all coastal protection measures were removed
  • Considering the possible implications of climate change and sea level rise. What impact will projected forecasts of more extreme weather events and rising sea level have on existing coastal management schemes

Dots

Technique one: Beach profiles

Aims

  • To survey the shape (morphology) of a beach
  • To compare beaches or coastlines in different locations
  • To examine the effects of management on beach processes and morphology
  • To investigate seasonal changes in the beach profile
  • To examine relationships between the beach profile and other factors, for example rock type, cliff profile, sediment size or shape

Equipment

  • Tape measure
  • Ranging poles
  • Clinometer or pantometer
  • Compass
  • Recording sheet

Methodology

  1. Select sampling points for beach profiles across the width of the beach
  2. At each sample point in turn, place a ranging pole at the start and finish (at A and H on the diagram). Point A should ideally be the low tide mark, or as close to this as is safe
  3. Note the main changes in slope angle up the beach, and use them to inform the ‘sections' for the profile. (A through to H on the diagram)
  4. For each change in slope, use the clinometer to take a bearing to record the slope angle (ii). For example, from point A to point B in the diagram below. It is important to ensure that the bearing is taken from a point on the ranging pole that coincides with the eye level of the person using the clinometer. Many ranging poles have stripes which can be used for this purpose. Alternatively, bearings can be taken from the eye level of a person of a similar height holding the ranging pole
  5. Measure the distance along the ground of the section (i), and record this information alongside the slope angle
  6. Repeat processes four and five for each break in slope that you have identified

Figure one: Surveying the morphology of the beach using a clinometer and ranging poles. Data collected using this technique can be used to create beach profiles.

Figure one: Surveying the morphology of the beach using a clinometer and ranging poles. Data collected using this technique can be used to create beach profiles.

Pantometers can be used by one person, and the slope can be surveyed systematically at regular, short intervals.

Figure two: Using a clinometer to measure the angle of a beach profile.

Figure two: Using a clinometer to measure the angle of a beach profile.

Considerations and possible limitations

  • Varying tidal conditions can affect access and safety. Make sure you check tide times before you embark on your fieldwork
  • Low tide is the best time to measure beach profiles, but places a time constraint on the activity. This can be overcome if groups of students complete profiles at different locations simultaneously and share their results
  • It is important to ensure that the ranging poles are held straight and prevented from sinking into sand, both of which may affect angle readings
  • Sampling technique is an important consideration. A balance needs to be struck between time available and the need for a number of profiles across the width of the beach to ensure the validity of results
  • There may be some user error when taking readings with a clinometer, and the sophistication of models of clinometer can vary enormously
  • If using a pantometer, this piece of equipment must be kept vertical when taking readings

Using the data within an investigation

  • Data can be used to draw profiles onto graph paper using distance from sea as the horizontal axis and using an angle measurer to complete the profiles. The graphs can then be analysed and comparisons made across the width of the beach
  • Profiles can be measured at different locations on the same stretch of coastline or in different seasons and compared
  • Different stretches of coastline which may have different natural characteristics, for example sand and shingle, or human characteristic, for example managed and unmanaged can also be compared
  • Beach profiles can be used in conjunction with other data collected to examine relationships between different variables

Dots

Technique two: Sediment analysis

Aims

  • To examine the sorting of beach material, either across the beach profile (following the sample lines used for profiling) or across the width of the beach (linking to the process of longshore drift)
  • To investigate the effect of management structures, for example groynes, on the sorting of beach material
  • To investigate the origin of beach material through the study of sediment cells
  • To compare sediment analysis at beaches in a range of locations and attempt to explain similarities and differences
  • To examine the relationship between beach sediment and other factors, for example the size and slope of the beach

Equipment

  • Clear ruler, pebble meter or stone-board
  • Roundness or angularity charts/indexes
  • Recording sheet
  • Quadrats (optional)
  • Random number table (optional)

Methodology

Techniques for measuring are the same as for sediment analysis in river studies. Please refer to this section for more information.

However, thought should be given to the sampling technique used to ensure that a representative sample is obtained.

Quadrats can be used to select sediment for sampling. Alternatively, ten surface pebbles touching your foot can be selected at each location. There are many different methods of sampling sediment. The different methods should be analysed by the researcher and an informed decision made as to which is the most appropriate for the aims of the investigation.

Considerations and possible limitations

  • Deciding on the sampling strategy is very important in reducing subjectivity and increasing the validity of results. A sampling method should always be adopted to avoid the temptation to select the pebbles
  • Sample size should be large enough to provide a representative sample of the ‘parent population', yet not too large to be unmanageable
  • The sharpest point of a stone must be measured when using the Cailleux scale and judgement of this may vary from person to person creating subjectivity
  • In reality, using Power's scale will reveal mostly class five/six
  • Anything which may affect the results should be noted, for example recent storms or management structures which may alter the composition of beach material

Dots

Technique three: Measuring longshore drift

Aims

  • To examine the transport of material along a stretch of coastline
  • To compare processes of sediment transport in different locations along the coastline
  • To investigate the effect of management techniques on the movement of beach material along the coastline
  • To examine the causes and effects of changes to the dominant direction of longshore drift

1. Observing swash and backwash, and transport of material

Equipment

  • Float, for example an orange or cork
  • Stopwatch
  • Tape measure

Methodology

  1. Decide on an appropriate distance to measure longshore drift over, for example 10 metres
  2. Lay out tape measure close to water and mark start and finish points
  3. Place your float into water in the breakwater zone at the start point
  4. Observe and time the object's movement across the pre-set distance

Similar results can be obtained if the distance travelled by the object is recorded over a specified time, for example five minutes.

Considerations and possible limitations

  • Tidal and wind conditions, the size and weight of float used and the slope angle of the beach may all affect measurements
  • Take note of the wind speed and direction on the day the fieldwork is undertaken as this may affect the speed at which the float is transported. This is particularly important if further sampling for the investigation is undertaken on another day
  • Obstructions to the movement of float, for example rocky outcrops, may affect results.
  • Floats may be lost during the investigation. Repeated experiments or the use of more than one marker can reduce this problem
  • Floats should be placed in the water ahead of the start line to allow them to settle prior to recording, and avoid giving the floats extra momentum
  • The float should lie low in the water to ensure that it is not influenced by the wind
  • The measuring should be undertaken in an area where there are no swimmers or paddlers for safety reasons and to ensure the reliability of results
  • Any anomalies should be recorded, for example obstructions which may affect the movement of the float
  • Weather and sea conditions can have a dramatic affect on observations

Using data within an investigation

  • Data would not be used in isolation, but in conjunction with other data collected as supporting evidence
  • Most commonly used when comparing managed and unmanaged stretches of coastline, particularly the impact of management techniques on transport processes within the sediment cell

2. Investigating the impact of groynes on the movement of sediment

Equipment

  • Metre ruler
  • Compass
  • Record sheet
  • Camera

Methodology

  1. Using the compass, identify and record the aspect of each side of the groyne, for example the western and eastern side of each groyne
  2. Use the meter ruler to measure from the top of the groyne to the surface of the sediment on each side
  3. Take digital pictures to illustrate differences in sediment levels
  4. Repeat for each groyne, or identify and use a suitable sampling strategy if there are too many groynes to sample them all

Considerations and possible limitations

  • Measurements should be taken at the same point along the length of each groyne, and tidal conditions and safety are therefore a consideration when undertaking this fieldwork
  • Care should be taken to ensure that the metre ruler doesn't sink into the sand, and that it is held straight

Using the data within an investigation

  • The findings of the investigation can be used to study the impact of physical and environmental processes on a stretch of coastline, including seasonal variations or variations in response to weather conditions, for example changes in the prevailing wind direction or storm events
  • Graphical representation of data can be used to compare sites
  • The data could be used within an investigation into the impact or success of coastal management strategies
  • A comparison of different sites could be made, comparing managed with unmanaged sites, or sites managed in different ways. The impact of coastal management strategies on other beaches further along the coastline can also be studied using this method.
  • Findings can be used to label and annotate images, see examples below from Swanage Beach in Dorset

Figure three: Annotated images of the beach at Swanage, Dorset showing evidence of longshore drift.

Figure three: Annotated images of the beach at Swanage, Dorset showing evidence of longshore drift.

Figure four: measuring the height of sediment to the west of a groyne

Figure four: Measuring the height of sediment to the west of a groyne

Keith Barlett from the Royal Manor Arts College in Dorset has written an article introducing an investigation which uses this methodology.

Dots

Technique four: Cliff surveys

Aims

  • To examine physical characteristics and features along a stretch of coastline
  • To identify different rock types and investigate the links between geology and physical features
  • To compare coastlines with different geologies
  • To study evidence of coastal erosion, including sub-aerial weathering, mass movement, basal erosion by the sea, human activity
  • To investigate and analyse strategies for protecting against coastal erosion

Equipment

  • Plain paper, pencil and rubber for sketch
  • Camera
  • Geological guides
  • Secondary evidence, for example photographs, maps, newspaper cuttings
  • Tape measure
  • Clinometer

Methodology

Cliff height

  • Standing a safe distance from the cliff, measure distance (A) using a tape measure. A distance of around 10 meters may be appropriate, but this depends on the size of the beach
  • Use a clinometer towards the top of the cliff to measure angle (B)
  • The height of the cliff is calculated as follows:
    • Distance (A) x tan of angle (B) + height of observer

Figure 5: The method for measuring the height of a cliff using a clinometer.

Figure 5: The method for measuring the height of a cliff using a clinometer.

Cliff sketch

A detailed sketch of the physical and human features of the cliffs at predetermined sampling points. Once cliff height has been established, the sketch can be drawn reasonably accurately to scale. Observations and annotations should be made of:

  • Obvious features, for example high tide level, caves, wave-cut notch, wave-cut platform, gullying
  • Basic geology (can be added later)
  • Structure, for example bedding planes and joints, folding and faulting
  • Conservation considerations, for example nesting birds, other animals
  • Type of vegetation and any evidence of effect on erosion
  • Evidence of erosion or mass movement, for example slumping, rock falls
  • Human activity, for example built structures, management/protection measures, recreational activities

Photographic evidence can also be used to support and reinforce sketches.

Considerations and possible limitations

  • Be aware of the safety implications of working close to cliffs, it can be dangerous
  • It is important to consider the sampling strategy, where to carry out cliff surveys and how many to do - before the investigation is started
  • There may be some user error when taking readings with a clinometer, and the sophistication of models of clinometer can vary enormously

Using the data within an investigation

  • Cliff profiles can be used in conjunction with other data collected to examine relationships between different variables, for example beach profiles or sediment analysis
  • An investigation could examine the links between the beach morphology, sediment and cliff features
  • An investigation could examine the links between the geology of the cliffs and beach material or movement
  • It is possible to compare different stretches of coastline with different geologies to see how they vary in terms of geology, sediment and beach morphology
  • Secondary data, for example historical maps, photographs or articles from local newspapers or websites can be used to examine recession rates. Predictions could be made for future rates of cliff recession, alongside suggestions for future management
  • A study of the range of different techniques used to manage the cliffs could highlight costs and benefits as well as potential impacts on physical processes and human activity. Each technique could be assessed in terms of its effectiveness at reducing rates of recession

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